Light emitting device and lighting apparatus having the same

ABSTRACT

A light emitting device includes a substrate including a plurality of convex portions, and a first semiconductor layer over the substrate. A plurality of first pits is provided in a top surface of the first semiconductor layer, and a plurality of second pits is provided in the top surface of the first semiconductor layer. A first metallic compound is provided in the first pits, and a second metallic compound is provided in the second pits. A second semiconductor layer is provided over the first semiconductor layer, and a light emitting structure is provided over the second semiconductor layer. The light emitting structure includes a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119(a) ofKorean Patent Application No. 10-2012-0115322 filed on Oct. 17, 2012,which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Field

The embodiment relates to a light emitting device and a lightingapparatus having the same.

2. Background

Groups III-V nitride semiconductors have been extensively used as mainmaterials for light emitting devices, such as a light emitting diode(LED) or a laser diode (LD), due to the physical and chemicalcharacteristics thereof. In general, the groups III-V nitridesemiconductors include a semiconductor material having a compositionalformula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, and 0≦x+y≦1).

The LED is a semiconductor device, which transmits/receives signals byconverting an electric signal into infrared ray or light using thecharacteristics of compound semiconductors. The LED is also used as alight source.

The LED or the LD using the nitride semiconductor material is mainlyused for the light emitting device to provide the light. For instance,the LED or the LD is used as a light source for various products, suchas a keypad light emitting part of a cellular phone, an electricsignboard, and a lighting device.

The above references are incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

SUMMARY

The embodiment provides a light emitting device including a siliconoxide disposed between the compound semiconductor layer and a convexportion of a substrate.

The embodiment provides a light emitting device including a siliconoxide in a pits corresponding to a convex portion of a substrate.

The embodiment provides a lighting apparatus having a light emittingdevice.

According to one embodiment, there is provided a light emitting deviceincluding a substrate including a plurality of convex portions; a firstsemiconductor layer disposed on the top surface of the substrate; aplurality of first pits disposed in a top surface of the firstsemiconductor layer and overlapped with the convex portions; a pluralityof second pits disposed in the top surface of the first semiconductorlayer and disposed in regions between the convex portions; a firstmetallic compound provided in the first pits to make contact with upperportions of the convex portions; a second metallic compound disposed inthe second pits; a first conductive semiconductor layer disposed on thefirst and second metallic compounds and the first semiconductor layer;an active layer on the first conductive semiconductor layer; and asecond conductive semiconductor layer on the active layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is a side sectional view showing a light emitting deviceaccording to the first embodiment.

FIG. 2 is a partially enlarged view of FIG. 1.

FIG. 3 is a plan view of the light emitting device of FIG. 1.

FIG. 4 is a sectional view showing an example of forming a firstsemiconductor layer on a substrate in a process of fabricating a lightemitting device according to the embodiment.

FIG. 5 is a sectional view showing an example of forming a metalliccompound layer on the first semiconductor layer of FIG. 4.

FIG. 6 is a sectional view after etching the metallic compound layer ofFIG. 5.

FIG. 7 is a sectional view showing an example of forming the secondsemiconductor layer and the light emitting structure on the firstsemiconductor layer and the metallic compound layer of FIG. 6.

FIG. 8 is a side sectional view of a light emitting device according tothe second embodiment.

FIG. 9 is a side sectional view of a light emitting device according tothe third embodiment.

FIG. 10 is a view of disposing an electrode on the light emitting deviceof FIG. 1.

FIG. 11 is a view of disposing an electrode and a light extractionstructure on the light emitting device of FIG. 1.

FIG. 12 is a view showing a vertical electrode disposed on the lightemitting device of FIG. 1.

FIG. 13 is a perspective view showing a light emitting device packagehaving the light emitting device of FIG. 9.

FIG. 14 is a side sectional view of the light emitting device package ofFIG. 13.

FIG. 15 is a perspective view showing a display apparatus having thelight emitting device or light emitting device package according to theembodiment.

FIG. 16 is a sectional view showing a display apparatus having the lightemitting device or light emitting device package according to theembodiment; and

FIG. 17 is an exploded perspective view showing a lighting device havingthe light emitting device or light emitting device package according tothe embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the description of the embodiments, it will be understood that, whena layer (or film), a region, a pattern, or a structure is referred to asbeing “on” or “under” another substrate, another layer (or film),another region, another pad, or another pattern, it can be “directly” or“indirectly” on the other substrate, layer (or film), region, pad, orpattern, or one or more intervening layers may also be present. Such aposition of the layer has been described with reference to the drawings.The thickness and size of each layer shown in the drawings may beexaggerated, omitted or schematically drawn for the purpose ofconvenience or clarity. In addition, the size of elements does notutterly reflect an actual size.

Hereinafter, embodiments will be described with reference toaccompanying drawings.

FIG. 1 is a perspective view showing a light emitting device accordingto the first embodiment. FIG. 2 is a partially enlarged view showing aconvex portion of the substrate of FIG. 1. FIG. 3 is a plan view of thelight emitting device of FIG. 1.

Referring to FIGS. 1 to 3, the light emitting device 100 includes asubstrate 111 having a plurality of convex portions 113, a firstsemiconductor layer 121 having pits 13 and 14, metallic compounds 123and 124, a second semiconductor layer 131, a first conductivesemiconductor layer 133, an active layer 135, and a second conductivesemiconductor layer 137.

The substrate 111 may include a transparent substrate, an insulatingsubstrate or a conductive substrate. For example, the substrate 111 mayinclude at least one of Al₂O₃, SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP,Ge, and Ga₂O₃. The substrate 111 may have a thickness T2 in the range of120 μm to 500 μm and a refractive index of 2.4 or less, or, for example,2 or less. The substrate 111 may include a sapphire substrate. Thesapphire substrate may include a transparent material. The sapphiresubstrate has a symmetric crystal structure of a hexa-rhombo (R3c). Thesapphire substrate has a lattice constant of 13.001 Å in a c-axisdirection, and a lattice constant of 4.765 Å in an a-axis direction. Inaddition, the sapphire substrate has C (0001) plane, A (1120) plane andR (1102) plane. Since the C (0001) plane of the sapphire substrateallows a nitride thin film to be easily grown and is stable at a hightemperature, the sapphire substrate is mainly used as a substrate forgrowing a nitride material, but the embodiment is not limited thereto.

The lengths of adjacent sides of the substrate 111 may be equal to ordifferent from each other. The adjacent sides may form an area of 0.3mm×0.3 mm or greater, or for example, a large area of 1 mm×1 mm orgreater. The substrate 111 may have a polygonal shape such as arectangular shape or a hexagonal shape.

The substrate 111 includes the plurality of convex portions 113. Theconvex portions 113 may be provided on an upper portion of the substrate111. The convex portions 113 may protrude in the direction of the activelayer 135.

The side sectional surface of each convex portion 113 may have asemi-sphere shape, a convex dome lens shape, or a convex lens shape andas another example, may have a polygonal shape, but the embodiment isnot limited thereto.

As shown in FIG. 3, the convex portions 113 may be spaced from eachother and may be arranged in the form of a lattice, a matrix and astripe shape. The gaps T1 may be formed between the convex portions 113regularly, irregularly or randomly, but the embodiment is not limitedthereto. The convex portion 113 allows the critical angle of theincident light to be changed, so that the light extraction efficiencycan be improved.

The bottom width D1 of the convex portion 113 may be formed at a rate inthe range 0.25 times to 4 times based on the distance G1 of the concaveregion 112. When the bottom width D1 of the convex portion 113 is out ofthe rate, the light extraction efficiency is not improved. Further, whenthe distance G1 of the concave region 112 is too short, a semiconductorlayer is not formed on the concave region 112. In addition, when thedistance G1 of the concave region 112 is too long, the improvement ofthe light extraction efficiency may be insufficient. The height H1 ofthe convex portion 113 may be formed at a rate in the range 0.3 times to8 times based on the distance G1 of the concave region 112 and the lightextraction efficiency may vary depending on the rate. When the height H1of the convex portion 113 is out of the above rate, the improvement ofthe light extraction efficiency may be insufficient. The bottom width D1of the convex portion 113 may be in the range of 1 μm to 4 μm and thedistance G1 of the concave portion 112 may be in the range of 1 μm to 4μm. In addition, the height H1 of the convex portion 113 may be in therange of 0.5 μm to 3.5 μm. The ranges of the bottom width D1 and heightH1 of the convex portion 113 and the distance G1 of the concave portion112 are proposed for preventing the concave region 112 from beingunformed and maximizing the light extraction efficiency.

A first semiconductor layer 121 may be formed on the substrate 11 byselectively using II to VI compound semiconductors. The firstsemiconductor layer 121 may be formed in at least one layer by using IIto VI compound semiconductors. For example, the first semiconductorlayer 121 may be formed by using a compound semiconductor materialhaving a compositional formula of Al_(y)In_(x)Ga_((1-x-y))N (0≦x≦1,0≦y≦1, 0≦x+y≦1). Typically, the first semiconductor layer 121 mayinclude at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN and AlInN.

The first semiconductor layer 121 may be prepared as an undopedsemiconductor layer. The undoped semiconductor layer may have electricalconductivity lower than that of an n-type semiconductor layer.

Since the convex portion 113 may include the inclined or curved surface,the first semiconductor layer 121 is not normally grown. Thus, if thefirst semiconductor layer 121 is grown at a predetermined thickness, thefirst semiconductor layer 121 is grown while being stacked on thecircumference of the convex portion 113. Then first pit is formed on theconvex portion 113 and a second pit 14 is formed along a dislocation 11on the first semiconductor layer 121. As shown in FIG. 3, a top surfaceof the first pits 13 has a hexagonal shape and a side sectional surfaceof the first pits 13 has V or U-shape. The second pits 14 have apolygonal shape and include a side sectional surface of a V or U-shape.A thickness of the first semiconductor layer 121 may be formed at athickness thicker than the height H1 of the convex portion 113. Forexample, the first semiconductor layer 121 may have a thickness in therange of 0.7 μm to 5.3 μm. Therefore, the first pit 13 has a depthdeeper than the vertex of the convex portion 113 and the depth may beexposed to one-third or more of the height H1 of the convex portion 113.The second pit 14 is formed in a concave shape having a predetermineddepth on the first semiconductor layer 121.

Dislocations 11 and 12 may be formed in the first semiconductor layer121. The dislocations 11 and 12 may be generated due to the latticeconstant difference between the surface of the substrate 111 and thefirst semiconductor layer. The generated dislocations 11 and 12 mayextend in a semiconductor growing direction, for example, in a verticaldirection. In addition, a part of the dislocations 11 and 12 may extendin the horizontal direction after it has been formed in the verticaldirection. The path of the dislocations 11 and 12 may be changed. One ofthe dislocations 11 and 12 extending in the vertical direction may becalled a vertical dislocation and a remaining part of the dislocations11 and 12 progressing to the horizontal direction from the verticaldirection may be called a horizontal dislocation. The dislocation may bedefined as a threading dislocation or a defect (dislocation). When thedislocations 11 and 12 are transferred to a top surface of the activelayer 135, an ESD characteristic may be deteriorated due to thedislocations 11 and 12, so this is a factor of decreasing thereliability of the light emitting device. According to the embodiment,the dislocations 11 and 12 are prevented from being transferred into theactive layer 135, so that the ESD characteristic is improved and theelectrical reliability of the light emitting device is improved.

When the first pit 13 is not formed on the first semiconductor layer121, the convex portions 113 are closed by the first semiconductor layer121. In this case, the second dislocations 12 in the first semiconductorlayer 121 are formed in a dislocation group on the convex portions 113again and the dislocation group is transferred to another layer. Inother words, a new dislocation is caused in an interface between thefirst semiconductor layer 121 and the vertexes of the convex portions113, and the new dislocation is grouped with any other dislocations andtransferred to any other layer. The dislocation generated as describedabove may more deteriorate the ESD characteristic when comparing withother dislocations. According to the embodiment, the first and secondpits 13 and 14 are formed in the first semiconductor layer 121. Themetallic compounds 123 and 124 are provided in the first and second pits13 and 14, so that a new dislocation may be generated through the firstand second pits 13 and 14, the transferring of the dislocation may berestrained. The first metallic compound 123 is provided in the firstpits 13 and makes contact with the surface of the convex portion 113 andthe inside of the first semiconductor layer 121. The second metalliccompound 124 is provided in the second pits 14. The second metalliccompound 24 may make contact with the first semiconductor layer 121 andthe first dislocation 11 disposed in the second pit 14. The inclinedsurface of the first metallic compounds 123 may be formed at the sameangle θ1 as that of the inclined surface of the first pit 13.

The lower width D3 of the first pit 13 corresponds to a direct length ofthe exposed region of the convex portion 113, and for example, may beformed in the range of 0.5 μm to 1 μm. The width of the first metalliccompound 123 may be narrower than or equal to the lower width D3 of thefirst pit 13, and may be equal to or narrower than the upper width D2 ofthe first pit 13. The first pit 13 is filled with the first metalliccompound 123, the lower surface of which may be concaved.

The first metallic compound 123 covers the side surface of the first pit13 in which the vertex of the convex portion 113 and the seconddislocations 12 are gathered, so that the dislocation may be preventedfrom being transferred into any other layers while growing asemiconductor layer and the crystalline of the nitride semiconductor maybe improved, so the electrical reliability and internal quantumefficiency may be improved. The first metallic compound 123corresponding to the vertex of the convex portion 113 may have a centralregion formed at a thin thickness, and the thickness of the firstmetallic compound 123 may be gradually thickened as going away from thevertex of the convex portion 113. Further, the second metallic compound124 is formed on the first dislocation 11 so that the second pit 14 maybe prevented from being transferred. The first metallic compound 123 mayblock the second dislocations 12 transferred to the first pit 13 and thesecond metallic compound 124 may block at least one dislocation 11transferred to the second pit 14.

The metallic compounds 123 and 124 may include at least one of aninsulating material, a metallic material and a metallic oxide. Themetallic compounds 123 and 124 may include silicon nitride or siliconoxide. The silicon nitride includes Si_(X)N_(Y) such as SiN or Si₃N₄.The silicon oxide may include SiOx such as SiO₂.

Since the first and second metallic compounds 123 and 124 haverefractive indexes different from those of the substrate 111 and thenitride semiconductor, external quantum efficiency may be improved. Aspace may be further formed between the first metallic compound 123 andthe convex portion 113. A medium such as air may be filled in the space.In addition, a space may be formed below the first metallic compound123, but the embodiment is not limited thereto.

In this case, a dislocation density of the first semiconductor layer 121is reduced. The dislocation density of the top surface of the firstsemiconductor layer 121 is reduced lower than that of the bottom surfaceof the first semiconductor layer 121. For example, the dislocationdensity of the top surface of the first semiconductor layer 121 isreduced by 70% or more based on the dislocation density of the bottomsurface of the first semiconductor layer 121. In addition, thedislocation density of the top surface of the first semiconductor layer121 is reduced lower than the dislocation density in the firstsemiconductor layer 121. Thus, the dislocation transferred from thefirst semiconductor layer 121 into the active layer 135 is reduced, sothat inside quantum efficiency may be improved. In addition, since themetallic compounds 123 and 124 are filled in all of the pits 13 and 14in the first semiconductor layer 121, the dislocation transferredthrough the pits 13 and 14 may be blocked by 100%, so that the surfacecrystalline of the second semiconductor layer 131 may be improved.

The second semiconductor layer 131 is formed on the first semiconductor121 and the first metallic compound 123. The bottom surface of thesecond semiconductor layer 131 may be formed in a concavo-convexstructure by the curved portion of the first pit 13 and the top surfacemay be flat. The second semiconductor layer 131 may prevent extension ofthe first and second pits 13 and 14 which exist in the firstsemiconductor layer 121 and may suppress or block the extension of thedislocations 11 and 12 existing in the first semiconductor layer 121.Thus, the defect density in the top surface of the second semiconductorlayer 131 is decreased to less than that in the first semiconductorlayer 121. For example, the defect density in the top surface of thesecond semiconductor layer 131 is decreased in the range of 1×10⁶ to1×10⁸ cm⁻². The crystal qualities of the second semiconductor layer 131and the light emitting structure 130 may be improved and the opticalpower of the light emitting device and the electrical reliability may beimproved.

The second semiconductor layer 131 may be formed by adding a firstconductive impurity or may be a semiconductor layer undoped with anyconductive impurities. The second semiconductor layer 131 may includethe first conductive semiconductor layer such as an N-type semiconductorlayer, but the embodiment is not limited thereto. For example, thesecond semiconductor layer 131 may be fowled by using a compoundsemiconductor material having a compositional formula ofAl_(y)In_(x)Ga_((1-x-y))N (0≦x≦1, 0≦y≦1, 0≦x≦1). Typically, the secondsemiconductor layer 131 may include at least one of GaN, InN, AlN,InGaN, AlGaN, InAlGaN and AlInN.

The light emitting structure 130 may be formed on the secondsemiconductor layer 131. The light emitting structure 130 may include agroup III-V compound semiconductor. For example, the light emittingstructure 130 may include semiconductors having the compositionalformula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1), so that thelight emitting structure 130 can emit the light having a predeterminedpeak wavelength in the wavelength range of an ultraviolet ray band to avisible ray band.

The light emitting structure 130 includes the first conductivesemiconductor layer 133, the second conductive semiconductor layer 137,and the active layer 135 between the first conductive semiconductorlayer 133 and the second conductive semiconductor layer 137.

The first conductive semiconductor layer 133 may be formed on the secondsemiconductor layer 131. The first conductive semiconductor layer 133may include a group III-V compound semiconductor doped with a firstconductive dopant. For example, the first conductive semiconductor layer133 may include one compound semiconductor such as GaN, InN, AlN, InGaN,AlGaN, InAlGaN or AlInN. For example, the first conductive semiconductorlayer 133 may be formed as an N type semiconductor layer having thecompositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1)and the first conductive dopant is an N type dopant including Si, Ge,Sn, Se or Te.

A superlattice structure including various semiconductor layersalternately stacked on each other may be formed between the firstconductive semiconductor layer 133 and the second semiconductor layer131. The superlattice structure may reduce the lattice defect. Eachlayer of the superlattice structure may have a thickness in the range ofa few Å.

A clad layer (not shown) may be formed between the first conductivesemiconductor layer 133 and the active layer 135. The clad layer mayinclude a GaN-based semiconductor and have a bandgap higher than that ofthe active layer 135. The clad layer may include an N-type semiconductorlayer and confines the carriers.

The active layer 117 is formed under the first conductive semiconductorlayer 115. The active layer 117 selectively includes a single quantumwell structure, a multiple quantum well (MQW) structure, a quantum wirestructure or a quantum dot structure and may have a periodicity of thewell layer and the barrier layer. The well layer may have acompositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y=1)and the barrier layer may have a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1). The well layer/barrierlayer may have at least one periodicity by using the stack structure ofInGaN/GaN, GaN/AlGaN, InGaN/AlGaN, InGaN/InGaN, InAlGaN/InAlGaN, orAlInN/InGaN. The barrier layer may include a semiconductor materialhaving a bandgap higher than that of the well layer.

The second conductive semiconductor layer 137 may include asemiconductor doped with a second conductive dopant. For example, thesecond conductive semiconductor layer 137 may include one of compoundsemiconductors such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN or AlInN.For example, the second conductive semiconductor layer 137 may be formedas a P type semiconductor layer having the compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1) and the secondconductive dopant is a P type dopant including Mg, Zn, Ca, Sr or Ba.

The second conductive semiconductor layer 137 may include a superlatticestructure, such as InGaN/GaN or AlGaN/GaN. The superlattice structure ofthe second conductive semiconductor layer 127 may spread the currentabnormally contained in the voltage, thereby protecting the active layer135.

In addition, the first conductive semiconductor layer 133 may beprepared as a P type semiconductor layer and the second conductivesemiconductor layer 137 may be prepared as an N type semiconductorlayer. A third conductive semiconductor layer having polarity oppositeto that of the second conductive semiconductor layer 137 may be formedunder the second conductive semiconductor layer 137.

The light emitting structure 130 may be defined by the first conductivesemiconductor layer 133, the active layer 135 and the second conductivesemiconductor layer 137. The light emitting structure 130 may beimplemented in one of an N-P junction structure, a P-N junctionstructure, an N-P-N junction structure, and a P-N-P junction structure.In this case, the symbols “N” and “P” represent N and P typesemiconductor layers, respectively, and the symbol “-” represents thattwo layers are directly or indirectly stacked on each other.Hereinafter, the second conductive semiconductor layer 137 will bereferred to as the uppermost layer of the light emitting structure 130for the purpose of convenience of explanation.

An electric power may be supplied to the first and second conductivesemiconductor layers 133 and 137 by connecting electrodes to the firstand second conductive semiconductor layers 133 and 137.

According to the embodiment, defects may be reduced in the active layer.The embodiment may provide a device having a greater resistance againstelectrostatic discharge (ESD). According to the embodiment, a lightabsorption may be minimized in a semiconductor and a scatteredreflection is generated so that light extraction efficiency may beimproved. According to the embodiment, the light emitting device ofblocking a dislocation caused on a convex portion is provided so thatelectrical reliability may be improved.

FIGS. 4 to 7 are views showing a process of fabricating a light emittingdevice. Although the following description is made based on theindividual device to facilitate the explanation, the light emittingdevice is manufactured in the wafer level and the individual device ismanufactured through the process described later. However, themanufacture of the individual device is not limited to the processdescribed later, but the process steps may be increased or reduced tomanufacture the individual device.

Referring to FIG. 4, the substrate 111 is loaded in growth equipment,and the compound semiconductor including group II to VI elements may beselectively used to be formed on the substrate 111 in the form of alayer or a pattern. The substrate 111 serves as a growth substrate.

The substrate 111 may include a transparent substrate, an insulatingsubstrate or a conductive substrate. For instance, the substrate 111 mayinclude one selected from the group consisting of Al₂O₃, GaN, SiC, ZnO,Si, GaP, InP, Ga₂O₃, and GaAs. The convex portions 113 are formed on thesubstrate 111. The convex portions 113 may be formed by etching thesubstrate 111 using a predetermined mask pattern disposed on thesubstrate 111.

A plurality of compound semiconductor layers may be grown on thesubstrate 111. The growth equipment for growing the compoundsemiconductor multilayer includes an E-beam evaporator, PVD (physicalvapor deposition) equipment, CVD (chemical vapor deposition) equipment,PLD (plasma laser deposition) equipment, a dual-type thermal evaporator,sputtering equipment, or MOCVD (metal organic chemical vapor deposition)equipment, but the embodiment is not limited thereto.

The first semiconductor layer 121 is grown on the substrate 111. Astrain is caused on the interface between the substrate 111 and thefirst semiconductor layer 121 due to a lattice constant difference. Thestress is caused by the dislocations 11 and 12 when growing the firstsemiconductor layer 121 and the dislocations 11 and 12 extend in thegrowing direction of the first semiconductor layer 121. In this case,the first semiconductor layer 121 is grown from a planar surface (0001)of the substrate through a surface of the convex portion 113. The firstpit 13 is formed on the convex portion 113 and the volume and size ofthe first pit 13 is adjusted by controlling the growing temperature ofthe first semiconductor layer 121. The first pit 13 may be exposed asthe second dislocation 12 extends. The second pit 14 may be formed onthe first dislocation 11 of the dislocations 11 and 12.

Referring to FIG. 5, a metallic compound layer 123A may be formed on thefirst semiconductor layer 121. The metallic compound layer 123A may beformed from the top surface of the first semiconductor layer 121 at apredetermined thickness. The metallic compound 123A may include siliconnitride or silicon oxide. The silicon nitride includes Si_(x)N_(y) suchas SiN or Si₃N₄. The silicon oxide may include SiOx such as SiO₂. Inthis case, the first and second pits 13 and 14 are filled with themetallic compound layer 123A.

The metallic compound layer 123A may be formed in the same chamber. Thetemperature of forming the metallic compound layer 123A is in the rangeof 900° to 1100° and silicon precursor is supplied into the atmosphereof ammonia (NH3). The silicon precursor may include SiH4, Si2H6 or DTBSi(ditertiarybutyl silane). The pits 123 and 124 may be filled with themetallic compound layer 123A. The supply of the precursor is interruptedlater. The metallic compound layer 123A may include a pore which isgenerated when the metallic compound layer 123A is formed in the pits 13and 14. The pore minimizes a light absorption caused in thesemiconductor and generates a scattered reflection, so that the lightoutput may be increased.

Referring to FIGS. 5 and 6, the metallic compound layer 123A is etched.The metallic compound layer 123A is etched to the top surface of thefirst semiconductor layer 121 by using at least one of dry and wetetchings. The dry etching may be performed by using excimer (Cl₂+ArF),Ti:sapphire, or Nd-YAG laser. The wet etching may be performed by usingaqua regia, KOH, HNO₃, HCL, CH₃COOH, H₃PO₄, H₂SO₄, KOH in H₂O, KOH inethylene glycol (Ch₂OH₂OH), NaOH in H₂O, or NaOH in ethylene glycol.Although the etching temperature varies depending on an etching scheme,the etching temperature may be set in the range of 0° to 200°.

By the etching process, the first metallic compound 123 is provided inthe first pit 13 and the second metallic compound 124 is provided in thesecond pit 14.

Referring to FIG. 7, the second semiconductor layer 131 is formed on thefirst semiconductor layer 121 and the first metallic compound 123. Thesecond semiconductor layer 131 may be formed of a compound semiconductorthe same as or different from that of the first semiconductor layer 121.The second semiconductor layer 131 may be grown while filling the firstand second pits 13 and 14 by controlling vertical and horizontal growingspeeds. The growing speed may be controlled by a flow rate, a pressureand growing temperature of the precursor and the growing temperature maybe 100° or above.

A light emitting structure 130 including a first conductivesemiconductor layer 133, an active layer 135 and a second conductivesemiconductor layer 137 is formed on the second semiconductor layer 131.The light emitting structure 130 may be formed at three semiconductorlayers or more, but the embodiment is not limited thereto. In addition,one of the first and second conductive semiconductor layers 133 and 137or an adjacent layer thereto may include a superlattice structure havingone of AlGaN/GaN/InGaN or AlGaN/GaN/InGaN, but the embodiment is notlimited thereto.

Thus, the first metallic compound 123 is formed on the first pit 13 ofthe first semiconductor layer 121 formed on the convex portion 113 ofthe substrate, so that the dislocation transferred to another layerthrough a region of the convex portion 113 of the substrate 111 may beeffectively blocked.

FIG. 8 is a side sectional view showing a light emitting deviceaccording to the second embodiment. In the description of the secondembodiment, the same configurations as those of the first embodimentwill refer to the descriptions of the first embodiment.

Referring to FIG. 8, the buffer layer 120 of the light emitting deviceis disposed between the first semiconductor layer 121 and the substrate111, so that the buffer layer 120 attenuates the lattice mismatchbetween the substrate 111 and the first semiconductor layer 121. Thus,the dislocation transferred to the first semiconductor layer 121 may bereduced. The buffer layer 120 may have a thickness of several nm or lessand, for example, may include a material having the compositionalformula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1), but theembodiment is not limited thereto. In this case, when the convex portion113 has a shape of a hemisphere, the buffer layer 120 may not benormally grown at the curved portion.

The second semiconductor layer 132, which is disposed between the firstsemiconductor layer 121 and the first conductive semiconductor layer133, may be formed in a super-lattice structure having a multilayer. Thesecond semiconductor layer 132 may include a plurality of layers havingmutually different reflective indexes or mutually different materialsand thicknesses. The second semiconductor layer 132 may include at leasttwo pair-layers which are alternately stacked. The dislocationtransferred to the first conductive semiconductor layer 133 through thesuperlattice structure of the second semiconductor layer 132 may beblocked. One of the first and second layers may include a compoundsemiconductor having the compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1).

FIG. 9 is a side sectional view showing a light emitting deviceaccording to the third embodiment. In the description of the thirdembodiment, the same configurations as those of the first and secondembodiments will refer to the descriptions of the first and secondembodiments.

Referring to FIG. 9, the light emitting device includes a buffer layer120 and a first semiconductor layer 121 on the substrate 111.

A part 21 of the buffer layer 120 may be formed on the convex portion113 of the substrate 111 and in the vertex region of the convex portion113 to have a thickness less than that of the buffer layer 120.

The part 21 of the buffer layer 120 makes contact with the firstmetallic compound 123 in the first pit 13. The part 21 of the bufferlayer 120 may be provided in the first metallic compound 123 in anembedded form. The first metallic compound 123 may make contact with thepart 21 of the buffer layer 120 and the side surface of the first pit12, and may effectively block the dislocation which may be transferredthrough the convex portion 113.

FIG. 10 is a view showing an example of disposing a first light emittingdevice. An example of disposing an electrode on the light emittingdevice of FIG. 1 will be described, but the description of theconfiguration of FIG. 1 will be omitted. In the description of FIG. 10,an example of disposing an electrode on the light emitting device ofFIGS. 8 and 9 will be omitted.

Referring to FIG. 10, the light emitting device 101 includes a substrate111, first and second semiconductor layers 121 and 131, a metalliccompound 123, a light emitting structure 130, a current diffusion layer141 on the light emitting structure 130, a first electrode 142 on thefirst conductive semiconductor layer 133, and a second electrode 143 onthe electrode layer 141.

The electrode layer 141, which may be formed as a transparent currentdiffusion layer, is formed on the top surface of the second conductivesemiconductor layer 137. The electrode layer 141 may be formed of amaterial selected from the group consisting of ITO(indium tin oxide),IZO(indium zinc oxide), IZTO(indium zinc tin oxide), IAZO(indiumaluminum zinc oxide), IGZO(indium gallium zinc oxide), IGTO(indiumgallium tin oxide), AZO(aluminum zinc oxide), ATO(antimony tin oxide),GZO(gallium zinc oxide), ZnO, IrOx, RuOx, and NiO, and may include atleast one layer. The electrode layer 141 may include a reflectiveelectrode layer. The electrode layer 141 may include one selected fromthe group consisting of Al, Ag, Pd, Rh, Pt, Ir and an alloy having atleast two of the above elements.

The second electrode 145 may be formed on the second conductivesemiconductor layer 137 and/or the electrode layer 141, and may includean electrode pad. The second electrode 145 may form a current diffusionpattern of an arm structure or a finger structure. The second electrode145 may be formed of a metal having properties of an ohmic contact, anadhesive layer and a bonding layer and may have non-transparentproperty, but the embodiment is not limited thereto.

The second electrode may be 40% or less based on a top surface area ofthe second conductive semiconductor layer 137, for example, 20% or less,but the embodiment is not limited thereto.

The first electrode 143 is formed on the first conductive semiconductorlayer 143.

The first and second electrodes 143 and 145 may include one selectedfrom the group consisting of Ti, Ru, Rh, Ir, Mg, Zn, Al, In, Ta, Pd, Co,Ni, Si, Ge, Ag, Au, and an alloy thereof. The ESD characteristic may bereduced by suppressing the dislocation or pit in the light emittingstructure 130.

An insulating layer may be further formed on the surface of the lightemitting structure 130, so that the insulating layer may prevent anelectrical short between the layers of the light emitting structure 130and moisture infiltration.

FIG. 11 is a view showing another example of disposing a first lightemitting device. The description about several elements of FIG. 11 willbe referred to the description of FIG. 10. In the description of FIG.11, an example of disposing an electrode on the light emitting device ofFIGS. 8 and 9 will be omitted.

Referring to FIG. 11, in the light emitting device 102, the electrodelayer 141 is disposed below the light emitting structure 130. Theelectrode layer 141 may serve as a reflective electrode layer by using ametal. The first and second electrodes 142 and 143 may protrude downwardand may be mounted on the substrate by a connection member, such as abump.

The substrate 111 may have a thickness T3 in the range of 30 μm to 70μm, but the embodiment is not limited thereto. The substrate 111includes a plurality of convex portion 113 and a plurality ofprotrusions 114 on the top and bottom portions thereof. The convexportion 113 provided on the bottom portion may have a centercorresponding to or offset from a center of the protrusion 114 providedon the top portion. The protrusion 114 may have a hemi-sphere shape or apolygonal shape. Such a structure is disposed in a light extractiondirection, so that the light extraction efficiency can be improved.

FIG. 12 is a side sectional view showing a vertical electrode disposedon the light emitting device of FIG. 1.

Referring to FIG. 12, the light emitting device 103 includes the firstelectrode 151 above the light emitting structure 130 and the secondelectrode 150 below the light emitting structure 130. The secondsemiconductor layer 131 may be provided on the light emitting structure130 and the first electrode 151 and the first electrode 151 is providedon the second semiconductor layer 131.

The substrate 111 of FIG. 1 and the first semiconductor layer 121provided on the second semiconductor layer 131 are removed throughphysical and chemical schemes. The second semiconductor layer 131includes a conductive semiconductor layer such as an N-typesemiconductor layer.

The substrate in FIG. 1 is removed. The growth substrate may be removedthrough a physical scheme (for example, laser lift off scheme) and/or achemical scheme (for example, wet etching scheme), so that the secondconductive semiconductor layer 131 may be exposed by removing the firstsemiconductor layer. The first electrode 151 is formed on the secondsemiconductor layer 131 by performing an isolation etching process inthe direction of removing the growth substrate. Thus, the light emittingdevice, which includes the first electrode 151 on the light emittingstructure 130 and the second electrode 150 below the light emittingstructure 130 in a vertical electrode structure, may be fabricated.

The first electrode 151 may be provided in mutually different regionsand may have an arm pattern or a bridge pattern, but the embodiment isnot limited thereto. A region of the first electrode 151 may be used asa pad.

A plurality of first metallic compounds 123 provided on the secondsemiconductor layer 131 are spaced apart from each other. The firstmetallic compound 123 may improve the efficiency of extracting lightincident through the second semiconductor layer 131. The first metalliccompound 123 may protrude higher than the top surface of the secondsemiconductor layer 131.

The second electrode 150 may be formed below the light emittingstructure, that is, the second conductive semiconductor layer 137. Thesecond electrode 150 may include a plurality of conductive layers suchas a contact layer 153, a reflective layer 155, a bonding layer 157 anda conductive support member 159.

The contact layer 153 may include a permeable conductive material or ametallic material. For example, the contact layer 153 may be formed byusing a low-conductive material such as ITO, IZO, IZTO, IAZO, IGZO,IGTO, AZO or ATO, or metal such as Ni or Ag. The reflective layer 155may be formed below the contact layer 153. The reflective layer 155 maybe formed of a structure having at least one layer including a materialselected from the group consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg,Zn, Pt, Au, Hf and combination thereof. The reflective layer 155 maymake contact with a lower surface of the second conductive semiconductorlayer 137. The reflective layer 155 may make ohmic contact with thesecond conductive semiconductor layer 137 by using metal or alow-conductive material such as ITO, but the embodiment is not limitedthereto.

The bonding layer 157 may be formed below the reflective layer 155. Thebonding layer 157 may be formed by using barrier or bonding metal. Thebonding layer 157 may include at least one of Ti, Au, Sn, Ni, Cr, Ga,In, Bi, Cu, Ag, Ta and alloy thereof

The conductive supporting member 159 is formed below the bonding layer157. The conductive supporting member 159 may be formed of a conductivematerial such as Cu, Au, Ni, Mo, Cu—W, or a carrier wafer (for example,Si, Ge, GaAs, ZnO, SiC, . . . ) having dopant. As another example, thesupporting member 159 may be implemented by using a conductive sheet.

The light extraction structure such as a roughness may be formed on thetop surface of the second conductive semiconductor layer 131. Insulatinglayers may be formed on surfaces of the semiconductor layers 131 to 135.A light extraction structure such as a roughness may be formed on theinsulating layers.

FIG. 13 is a perspective view showing a light emitting device packagehaving the light emitting device. FIG. 14 is a side sectional view ofthe light emitting device of FIG. 13.

Referring to FIGS. 13 and 14, the light emitting device package 600includes a body 610 having a concave portion 660, first and second leadframes 621 and 631, a connecting frame 646, light emitting devices 603to 606, a molding member 651 and paste members 681 and 682. The concaveportion 660 may include first and second cavities 625 and 635.

The body 610 may include at least one of an insulating material, aconductive material and a metallic material. The body 610 may include atleast one of a resin material, such as Polyphthalamide (PPA), silicon(Si), a metallic material, photo sensitive glass (PSG), sapphire(Al2O3), and a printed circuit board (PCB). For example, the body 610may include a resin material such as Polyphthalamide (PPA).

The body 610 includes a plurality of side surfaces 611 to 614. A lengthof the first side surface 611 or the second side surface 612 maycorrespond to a length between the third and fourth side surfaces 613and 614 and the longitudinal direction may pass through the center ofthe second and third cavities 625 and 635.

The first and second lead frames 621 and 631 may be disposed on a lowersurface of the body 610 to be mounted on the circuit board. The firstand second lead frames 621 and 631 may have thicknesses of 0.2 mm±0.05mm.

The body 610 includes the concave portion 660 including an upper openedportion, a side surface 616A and a bottom 616.

The first lead frame 621 is disposed under a first region of the concaveportion 660. A first cavity 625, which has a depth lower than the bottomof the concave portion 616, is provided in a central portion of thefirst lead frame 621. The side surface and bottom 622 of the firstcavity 625 are formed by the first lead frame 621. The second lead frame631 is disposed in a second region spaced apart from the first region. Asecond cavity 635, which has a depth lower than the bottom 616 of theconcave portion 616, is provided in a central portion of the second leadframe 631. The side surface and bottom 632 of the second cavity 635 areformed by the second lead frame 631.

The central portions of the first and second lead frames 621 and 631 maybe exposed to a lower portion of the body 610 and may be disposed on aplane which is the same as or different from a lower surface of the body610.

The first lead frame 621 may include a first lead part 623, which mayprotrude from the third side surface 613 of the body 610. The secondlead frame 621 may include a second lead part 633, which may protrudefrom the fourth side surface 614 facing the third side surface 613 ofthe body 610. The first and second lead frame 621 and 623 and theconnecting frame 646 may include a metallic material, for example, atleast one of titanium (Ti), copper (Cu), nickel(Ni), gold (Au), chrome(Cr), tantalum (Ta), platinum (Pt), tin (Sn), silver (Ag), and phosphor(P), and may be configured as a single metal layer or multilayer. Theconnecting frame 646 is disposed on the bottom 616 of the concaveportion 660. In addition, the connecting frame 646 is disposed betweenthe first and second lead frames 621 and 631 and serves as a middleconnecting terminal.

The first light emitting device 671 is disposed in the first cavity 625of the first lead frame 621, and the second light emitting device 672 isdisposed in the second cavity 635 of the second lead frame 631.

The first light emitting device 671 is connected to the first connectingframe 621 and the connecting frame 646 through the connecting members603 and 604. The second light emitting device 672 is connected to thesecond connecting frames 621 and the connecting frame 646 through theconnecting members 605 and 606. The connecting members may be preparedas a wire. A protective device may be disposed on a portion of the firstor second lead frame 621 or 631.

The molding member 651 may be formed in the concave portion 660, and thefirst and second cavities 625 and 635. The molding member 651 may beformed of a transparent resin material such as silicon or epoxy, and maybe formed in a single layer or a multilayer.

A first paste member 681 is disposed between the first light emittingdevice 671 and the bottom 622 of the first cavity 625 such that thefirst light emitting device 671 and the bottom 622 of the first cavity625 are adhesive and electrically connected to each other. A secondpaste member 682 is disposed between the second light emitting device672 and the bottom 632 of the second cavity 635 such that the secondlight emitting device 672 and the bottom 632 of the second cavity 635are adhesive and electrically connected to each other. The first andsecond pastes 681 and 682 include an insulation adhesive such as epoxy.Filler may be added to the epoxy, but the embodiment is not limitedthereto.

The molding member 651 may include phosphor for converting a wavelengthof light emitted to the light emitting devices 671 and 672. The phosphormay be added to the molding member 651 formed in at least one region ofthe first and second cavities 625 and 635, but the embodiment is notlimited thereto. The phosphor excites a part of the light emitted fromthe light emitting devices 671 and 672 to emit the light having anotherwavelength. The phosphor may include one selected from YAG, TAG,Silicate, Nitride, and oxy-nitride materials. The phosphor may includeat least one of a red phosphor, a yellow phosphor, and a green phosphor,but the embodiment is not limited thereto. A top surface of the moldingmember 651 may have at least one of a flat shape, a concave shape and aconvex shape. For example, the top surface of the molding member 651 maybe formed in a concave shape which may serve as a light exit surface.

While the current embodiment shows and describes the top view type lightemitting device package, the light emitting device package may beimplemented by a side view type light emitting device package to provideimproved effects in the heat releasing characteristic, conductivity andreflective characteristic. In the top view type or side view type lightemitting device package, after the resin layer is formed of a resinmaterial, a lens may be formed or attached on the resin layer, but thepresent invention is not limited thereto.

<Lighting System>

The light emitting device according to the embodiment is applicable to alighting system. The lighting system includes a structure in which aplurality of light emitting devices are arrayed. The lighting systemincludes a display apparatus shown in FIGS. 15 and 16, a lightingapparatus shown in FIG. 17, a lighting lamp, a camera flash, a signallamp, a headlamp for a vehicle, and an electronic display.

FIG. 15 is an exploded perspective view showing a display apparatushaving the light emitting device according to the embodiment.

Referring to FIG. 15, a display apparatus 1000 according to theembodiment includes a light guide plate 1041, a light source module 1031to supply light to the light guide plate 1041, a reflective member 1022under the light guide plate 1041, an optical sheet 1051 on the lightguide plate 1041, a display panel 1061 on the optical sheet 1051, and abottom cover 1011 to receive the light guide plate 1041, the lightsource module 1031, and the reflective member 1022, but the embodimentis not limited thereto.

The bottom cover 1011, the reflective sheet 1022, the light guide plate1041, the optical sheet 1051, and the light unit 1050 may be defined asa backlight unit.

The light guide plate 1041 diffuses the light supplied from the lightsource module 1033 to provide surface light. The light guide plate 1041may include a transparent material. For example, the light guide plate1041 may include one of acryl-based resin, such as PMMA (polymethylmethacrylate, PET (polyethylene terephthalate), PC (polycarbonate), COC(cyclic olefin copolymer) and PEN (polyethylene naphtha late) resin.

The light source module 1031 is disposed on at least one side of thelight guide plate 1041 to supply the light to at least one side of thelight guide plate 1041. The light source module 1031 serves as the lightsource of the display device.

At least one light source module 1031 is disposed to directly orindirectly supply the light from one side of the light guide plate 1041.The light source module 1031 may include a board 1033 and the lightemitting device according to the embodiments or the light emittingdevice 1035. The light emitting device or the light emitting device 1035are arranged on the board 1033 while being spaced apart from each otherat the predetermined interval.

The board 1033 may include a printed circuit board (PCB) including acircuit pattern (not shown). In addition, the board 1031 may alsoinclude a metal core PCB (MCPCB) or a flexible PCB (FPCB) as well as atypical PCB, but the embodiment is not limited thereto. If the lightemitting device 1035 is installed on the side of the bottom cover 1011or on a heat dissipation plate, the board 1033 may be omitted. The heatdissipation plate partially makes contact with the top surface of thebottom cover 1011.

In addition, the light emitting device 1035 are arranged such that lightexit surfaces to discharge light of the light emitting device 1035 arespaced apart from the light guide plate 1041 by a predetermined distanceon the board 1033, but the embodiment is not limited thereto. The lightemitting device 1035 may directly or indirectly supply the light to alight incident surface, which is one side of the light guide plate 1041,but the embodiment is not limited thereto.

The reflective member 1022 is disposed below the light guide plate 1041.The reflective member 1022 reflects the light, which is traveleddownward through the bottom surface of the light guide plate 1041,toward the display panel 1061, thereby improving the brightness of thelight unit 1050. For example, the reflective member 1022 may includePET, PC or PVC resin, but the embodiment is not limited thereto. Thereflective member 1022 may serve as the top surface of the bottom cover1011, but the embodiment is not limited thereto.

The bottom cover 1011 may receive the light guide plate 1041, the lightsource module 1031, and the reflective member 1022 therein. To this end,the bottom cover 1011 has a receiving section 1012 having a box shapewith an opened top surface, but the embodiment is not limited thereto.The bottom cover 1011 can be coupled with the top cover (not shown), butthe embodiment is not limited thereto.

The bottom cover 1011 can be manufactured through a press process or anextrusion process by using metallic material or resin material. Inaddition, the bottom cover 1011 may include metal or non-metallicmaterial having superior thermal conductivity, but the embodiment is notlimited thereto.

The display panel 1061, for example, is an LCD panel including first andsecond transparent substrates, which are opposite to each other, and aliquid crystal layer interposed between the first and second substrates.A polarizing plate can be attached to at least one surface of thedisplay panel 1061, but the embodiment is not limited thereto. Thedisplay panel 1061 displays information by allowing the light to passtherethrough. The display device 1000 can be applied to various portableterminals, monitors of notebook computers, monitors or laptop computers,and televisions.

The optical sheet 1051 is disposed between the display panel 1061 andthe light guide plate 1041 and includes at least one transmissive sheet.For example, the optical sheet 1051 includes at least one selected fromthe group consisting of a diffusion sheet, a horizontal and verticalprism sheet, and a brightness enhanced sheet. The diffusion sheetdiffuses the incident light, the horizontal and vertical prism sheetconcentrates the incident light onto the display panel 1061, and thebrightness enhanced sheet improves the brightness by reusing the lostlight. In addition, a protective sheet can be disposed on the displaypanel 1061, but the embodiment is not limited thereto.

The light guide plate 1041 and the optical sheet 1051 can be disposed inthe light path of the light source module 1031 as optical members, butthe embodiment is not limited thereto.

FIG. 16 is a sectional view showing a display apparatus according to theembodiment.

Referring to FIG. 16, the display device 1100 includes a bottom cover1152, a board 1120 on which the light emitting device 1124 are arrayed,an optical member 1154, and a display panel 1155.

The board 1120 and the light emitting device 1124 may constitute thelight source module 1160. In addition, the bottom cover 1152, at leastone light source module 1160, and the optical member 1154 may constitutethe light unit 1150. The bottom cover 1151 can be disposed with areceiving section 1153, but the embodiment is not limited thereto. Thelight source module 1160 includes a board 1120, and a plurality of lightemitting devices arranged on the board 1120 or a light emitting device1124.

The optical member 1154 may include at least one selected from the groupconsisting of a lens, a light guide plate, a diffusion sheet, ahorizontal and vertical prism sheet, and a brightness enhanced sheet.The light guide plate may include PC or PMMA (Poly methyl methacrylate).The light guide plate can be omitted. The diffusion sheet diffuses theincident light, the horizontal and vertical prism sheet concentrates theincident light onto a display region, and the brightness enhanced sheetimproves the brightness by reusing the lost light.

The optical member 1154 is disposed above the light source module 1160in order to convert the light emitted from the light source module 1160into the surface light.

FIG. 17 is an exploded perspective view showing a lighting device havingthe light emitting device according to the embodiment.

Referring to FIG. 17, the lighting device according to the embodimentmay include a cover 2100, a light source module 2200, a heat radiationmember 2400, a power supply part 2600, an inner case 2700, and a socket2800. In addition, the light emitting device according to the embodimentmay further include at least one of a member 2300 and a holder 2500. Thelight source module 2200 may include the light emitting device accordingto the embodiment.

For example, the cover 2100 has the shape of a bulb, or a hemisphericalshape. The cover 2100 may have a hollow structure, and a portion of thecover 2100 may be open. The cover 2100 may be optically connected to thelight source module 2200, and may be coupled with the heat radiationmember 2400. The cover 2100 may have a recess part coupled with the heatradiation member 2400.

The inner surface of the cover 2100 may be coated with ivory whitepigments serving as a diffusing agent. The light emitted from the lightsource module 2200 may be scattered or diffused by using the ivory whitematerial, so that the light can be discharged to the outside.

The cover 2100 may include glass, plastic, PP, PE, or PC. In this case,the PC represents superior light resistance, superior heat resistance,and superior strength. The cover 2100 may be transparent so that thelight source module 2200 may be recognized at the outside. In addition,the cover 2100 may be opaque. The cover 2100 may be formed through ablow molding scheme.

The light source module 2200 may be disposed at one surface of the heatradiation member 2400. Accordingly, the heat emitted from the lightsource module 2200 is conducted to the heat radiation member 2400. Thelight source module 2200 may include a light emitting device 2210, aconnection plate 2230, and a connector 2250.

The member 2300 is disposed on the top surface of the heat radiationmember 2400, and has a guide groove 2310 having a plurality of lightemitting devices 2210 and a connector 2250 inserted into the guidegroove 2310. The guide groove 2310 corresponds to the substrate of thelight emitting device 2210 and the connector 2250.

White pigments may be applied to or coated on the surface of the member2300. The member 2300 reflects light, which reflected by the innersurface of the cover 2100 to return to the light source module 2200,toward the cover 2100. Accordingly, the light efficiency of the lightingapparatus according to the embodiment can be improved.

The member 2300 may include an insulating material. The connection plate2230 of the light source module 2200 may include an electric-conductivematerial. Accordingly, the heat radiation member 2400 may beelectrically connected to the connection plate 2230. The member 2300includes an insulating material to prevent the electrical short betweenthe connection plate 2230 and the heat radiation member 2400. The heatradiation member 2400 receives heat from the light source module 2200and the heat from the power supply part 2600 and radiates the heats.

The holder 2500 blocks a receiving groove 2719 of an insulating part2710 disposed in an internal case 2700. Accordingly, the power supplypart 2600 received in the insulating part 2710 of the internal case 2700is sealed. The holder 2500 has a guide protrusion part 2510. The guideprotrusion part 2510 may include a hole allowing a protrusion part 2610of the power supply part 2600 to pass therethrough.

The power supply part 2600 processes and transforms an electrical signalreceived from the outside and supplies the electrical signal to thelight source module 2200. The power supply part 2600 is received in thereceiving groove 2719 of the internal case 2700, and sealed in theinternal case 2700 by the holder 2500.

The power supply part 2600 may include a protrusion part 2610, a guidepart 2630, a base 2650, and an extension part 2670.

The guide part 2630 protrudes outward from one side of the base 2650.The guide part 2630 may be inserted into the holder 2500. A plurality ofparts may be disposed on one surface of the base 2650. For example, theparts include a DC converter, a driving chip to drive the light sourcemodule 2220, and an ESD (electrostatic discharge) protective device toprotect the light source module 2200, but the embodiment is not limitedthereto.

The extension part 2670 protrudes outward from another side of the base2650. The extension part 2670 is inserted into the connection part 2750of the internal case 2700, and receives an electrical signal from theoutside. For example, the extension part 2670 may be equal to or lessthan the width of the connection part 2750 of the internal case 2700.The extension part 2670 may be electrically connected to the socket 2800through a wire.

The internal case 2700 may be disposed therein with a molding parttogether with the power supply part 2600. The molding part is formed byhardening a molding liquid, so that the power supply part 2600 may befixed into the internal case 2700.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A light emitting device comprising: a substrateincluding a plurality of convex portions; a first semiconductor layerprovided over top surface of the substrate; a plurality of first pitsprovided on a top surface of the first semiconductor layer andoverlapped with the convex portions; a plurality of second pits providedon the top surface of the first semiconductor layer and disposed inregions between the convex portions; a first metallic compound providedin the first pits and contacted with upper portions of the convexportions; a second metallic compound provided in the second pits; asecond semiconductor layer provided over the first semiconductor layer;and a light emitting structure provided over the second semiconductorlayer, wherein the light emitting structure comprises a first conductivesemiconductor layer on the second semiconductor layer, an active layeron the first conductive semiconductor layer, and a second conductivesemiconductor layer on the active layer.
 2. The light emitting device ofclaim 1, wherein the first semiconductor layer includes a plurality ofdislocations connected to the first and second pits, respectively. 3.The light emitting device of claim 2, wherein the dislocations connectedto the first pits progress from a vertical direction.
 4. The lightemitting device of claim 1, wherein the first and second metalliccompounds include an insulating material.
 5. The light emitting deviceof claim 1, wherein the first and second metallic compounds includenitride or oxide including silicon.
 6. The light emitting device ofclaim 1, wherein a lower portion of the first metallic compound includesa concave curved surface.
 7. The light emitting device of claim 1,wherein a side surface of the first metallic compound is inclined at aninclined angle equal to an inclined angle of a side surface of the firstpit.
 8. The light emitting device of claim 1, wherein the first metalliccompound has a lower width narrower than a lower width of each convexportion.
 9. The light emitting device of claim 1, wherein each convexportion has a hemisphere shape and a lower width of each convex portionis larger than a height of each convex portion.
 10. The light emittingdevice of claim 1, wherein at least one of the first and secondsemiconductor layers includes an n-type dopant.
 11. The light emittingdevice of claim 1, wherein the second pits have depths less than depthsof the first pits, and are placed at positions higher than positions ofthe convex portions.
 12. The light emitting device of claim 1, whereintop surfaces of the first and second metallic compounds are aligned on asame horizontal plane with the top surface of the first semiconductorlayer.
 13. The light emitting device of claim 1, further comprising abuffer layer between the substrate and the first semiconductor layer,wherein a part of the buffer layer is disposed between the firstmetallic compound and the convex portion, and the first metalliccompound makes contact with a circumstance of a part of the bufferlayer.
 14. The light emitting device of claim 1, further comprising apore between at least one of the convex portions and the first metalliccompound.
 15. The light emitting device of claim 1, wherein adislocation density of a top surface of the second semiconductor layeris less than a dislocation density in the first semiconductor layer andis in a range of 1×10⁶ cm⁻² to 1×10⁸ cm⁻².
 16. The light emitting deviceof claim 1, wherein the first and second metallic compounds comprise amaterial different from materials of the first and second semiconductorlayers.
 17. A light emitting device comprising: a substrate including alight transparent material and including a plurality of convex portions;a first semiconductor layer provided over the top surface of thesubstrate; a plurality of first pits provided on a top surface of thefirst semiconductor layer and overlapped with the convex portions; aplurality of second pits provided on the top surface of the firstsemiconductor layer and disposed in regions between the convex portions;a first metallic compound provided in the first pits and contacted withupper portions of the convex portions; a second metallic compoundprovided in the second pits; a second semiconductor layer provided overthe first semiconductor layer; and a light emitting structure providedover the second semiconductor layer, wherein the light emittingstructure comprises a first conductive semiconductor layer on the secondsemiconductor layer, an active layer on the first conductivesemiconductor layer, and a second conductive semiconductor layer on theactive layer, the first and second metallic compounds comprise amaterial different from materials of the first and second semiconductorlayers, and each first metallic compound has a volume greater than avolume of each second metallic compound.
 18. The light emitting deviceof claim 16, wherein the first semiconductor layer has a thicknesslarger than a height of each convex portion, and the first pits havedepths deeper than depths of the second pits.
 19. A light emittingdevice comprising: a substrate including a light transparent materialand including a plurality of convex portions; a plurality of protrusionsprotruding from a bottom surface of the substrate; a first semiconductorlayer provided over the top surface of the substrate; a plurality offirst pits provided on a top surface of the first semiconductor layerand overlapped with the convex portions; a plurality of second pitsprovided on the top surface of the first semiconductor layer anddisposed in regions between the convex portions; a first metalliccompound provided in the first pits and contacted with upper portions ofthe convex portions; a second metallic compound provided in the secondpits; a second semiconductor layer provided over the first semiconductorlayer; and a light emitting structure over the second semiconductorlayer, wherein the light emitting structure comprises a first conductivesemiconductor layer on the second semiconductor layer, an active layeron the first conductive semiconductor layer, and a second conductivesemiconductor layer on the active layer, the first and second metalliccompounds comprise a material different from materials of the first andsecond semiconductor layers, each first metallic compound has a volumegreater than a volume of each second metallic compound, and the firstmetallic compound includes top surfaces having horizontal surfacesaligned on a same horizontal plane with the top surface of the firstsemiconductor layer and side surfaces inclined at the same angle as aside surface of the first pit.
 20. The light emitting device of claim19, wherein the first metallic compound includes a plurality of inclinedside surfaces making contact with the first semiconductor layer, and aconcave bottom surface making contact with surfaces the convex portions.